Ink-jet recording device

Abstract

To provide an ink-jet recording device, with a simple configuration, capable of reducing residual air and solid matter in a negative pressure regulating valve, while also preventing inflow of air bubbles into nozzles of a recording head.SOLUTION: An ink-jet recording device comprises an ink container, one or more recording heads, an ink channel, a negative pressure regulating valve, a cap, a suction pump, and a waste ink discharge channel. The ink-jet recording device can perform suction purging in which air in a sealed space between an ink discharge surface and the cap is sucked by the suction pump. The negative pressure regulating valve has an inflow-side pressure chamber, an outflow-side pressure chamber, a communication hole, a first outflow hole formed below the communication hole of the outflow-side pressure chamber to communicate with a first outflow passage, a second outflow hole formed above the communication hole of the outflow-side pressure chamber to communicate with a second outflow passage, and a valve member that opens and closes the communication hole. The first outflow passage and the second outflow passage communicate with the recording head, and have a first opening and closing valve that opens and closes the first outflow passage, and a second opening and closing valve that opens and closes the second outflow passage.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an inkjet recording apparatus equipped with a negative pressure adjusting valve. [Background technology]

[0002] In inkjet recording devices, it is important to maintain constant ink ejection conditions and ejection states in order to ensure high print quality. To address this issue, a pressure adjustment unit (negative pressure adjustment valve, damper, etc.) is installed in the ink flow path connecting the ink container and the recording head to store ink and adjust the pressure.

[0003] Patent Document 1 discloses a liquid ejection device having a pressure adjustment unit (negative pressure adjustment valve) that is provided in a liquid flow path connecting a liquid storage unit and a liquid ejection head and stores liquid to adjust the pressure. The pressure adjustment unit has a liquid storage unit that has a liquid outlet hole that communicates with the liquid ejection head and a communication hole that communicates with the liquid storage unit. The liquid storage unit has a displacement wall portion on part of its outer surface that displaces in response to the pressure inside the liquid storage unit.

[0004] Patent Document 2 discloses a liquid storage mechanism (negative pressure adjustment valve) that is provided between a liquid supply unit on the device main body and an inkjet printhead, and that includes a pressure chamber that stores liquid to be supplied to the inkjet printhead, with the pressure chamber having a liquid supply port and a liquid outlet located higher than the bottom of the pressure chamber. The liquid storage mechanism connects a first flow path that flows the liquid in the pressure chamber toward the printhead to the liquid outlet, connects one side of a second flow path to the bottom of the pressure chamber, and connects the other side of the second flow path to the first flow path, with the flow path resistance of the second flow path set greater than the flow path resistance of the first flow path, and the pressure chamber forms a damper mechanism that absorbs pressure fluctuations applied to the ink in the inkjet printhead.

[0005] Patent Document 3 discloses a valve unit installed midway through a flow path of a printing device that includes a storage section for storing ink, a discharge section for discharging the ink, and a flow path through which the ink passes from the storage section to the discharge section. The valve unit has a first chamber that communicates with the storage section, a second chamber that communicates with the discharge section, a switching valve that switches between passing and blocking ink from the first chamber to the second chamber, and a discharge section that discharges sediment from the second chamber by suction. The valve unit has a flow path that flows out to the discharge section (recording head) at a vertically upper portion of the second chamber (outlet pressure chamber), and an outflow path (discharge section) at a vertically lower portion for discharging solidified material or foreign matter. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-166194 [Patent Document 2] Japanese Patent Application Publication No. 2018-149685 [Patent Document 3] Japanese Patent Application Publication No. 2018-1516 Summary of the Invention [Problem to be solved by the invention]

[0007] The outlet pressure chamber of the above-mentioned negative pressure regulating valve has a large volume due to the presence of a diaphragm (displacement wall) that is in contact with the atmosphere and determines the threshold pressure for opening and closing the valve. Therefore, when the valve is opened, the flow rate of the liquid flowing in from the inlet pressure chamber slows, creating areas where the flow stagnates. As a result, when an attempt is made to fill the negative pressure regulating valve from an empty state with liquid, air tends to remain in the outlet pressure chamber, and a large amount of liquid must be flowed to expel the air.

[0008] Furthermore, if the printer is shipped with an initial filler liquid, and the ink is replaced with ink during installation, if the ink is pigment ink, the ink density will be higher than that of the initial filler liquid due to the pigment dispersion. Therefore, the initial filler liquid, which has a low density, tends to remain at the top of the outlet pressure chamber and is difficult to replace with ink. As a result, a large amount of ink must be flushed to completely replace the initial filler liquid with ink. Furthermore, if ink components solidify or foreign matter is mixed in during the printer's use, the solidified matter or foreign matter tends to remain at the bottom of the outlet pressure chamber. As a result, if the solidified matter or foreign matter gets caught in the valve opening and closing section, the valve will not close.

[0009] In the configuration of Patent Document 1, the flow path leading to the outflow pressure chamber toward the recording head is arranged only on the vertically lower side, which causes a problem that air or initial filling liquid tends to remain in the upper part of the outflow pressure chamber.In the configuration of Patent Document 2, the flow path leading to the outflow pressure chamber toward the recording head is arranged only on the vertically upper side, which causes a problem that solids and foreign matter tend to remain in the lower part of the outflow pressure chamber.

[0010] In the configuration of Patent Document 3, the outflow path is connected to a dedicated suction means. In other words, the suction means is not connected downstream of the ejection portion. Therefore, if the absolute value of the negative pressure of the suction means is too large, the meniscus inside the nozzle of the recording head may be drawn in through the valve unit, causing air bubbles to enter the nozzle and leading to ink non-ejection. Conversely, if the absolute value of the negative pressure of the suction means is too small, there is a problem in that solidified material or foreign matter cannot be efficiently discharged.

[0011] In view of the above problems, the present invention aims to provide an inkjet recording device that can suppress the retention of air and solid matter in a negative pressure adjustment valve with a simple configuration and also suppress the inflow of air bubbles into the nozzles of the recording head. [Means for solving the problem]

[0012] To achieve the above object, a first aspect of the present invention is an inkjet recording device including an ink container, one or more recording heads, an ink flow path, a negative pressure adjustment valve, a cap, a suction pump, and a waste ink discharge flow path. The ink container stores ink. The recording head has a plurality of nozzles that eject ink. The ink flow path connects the ink container to the recording head. The negative pressure adjustment valve is connected to the ink flow path. The cap is attached to the ink ejection surface of the recording head and can form a sealed space between the cap and the ink ejection surface. The suction pump sucks air inside the cap. The waste ink discharge flow path discharges liquid sucked into the inside of the cap by the suction pump. With the cap attached to the ink ejection surface, the inkjet recording device can perform a suction purge process in which the suction pump sucks air from the sealed space and forcibly discharges ink from all nozzles of the recording head. The negative pressure adjustment valve has an inlet pressure chamber, an outlet pressure chamber, a communication hole, a first outlet hole, a second outlet hole, and a valve member. The inlet pressure chamber has an ink inlet hole that communicates with an ink inlet path, which is an ink flow path on the ink container side. The outlet pressure chamber communicates with an ink outlet path, which is an ink flow path on the recording head side. The communication hole communicates the inlet pressure chamber with the outlet pressure chamber. The first outlet hole is formed below the communication hole of the outlet pressure chamber and communicates with the first outlet path, which is an ink outflow path. The second outlet hole is formed above the communication hole of the outlet pressure chamber and communicates with the second outflow path, which is an ink outflow path. The valve member is inserted into the communication hole and is movable between a closed position that closes the communication hole and an open position that opens the communication hole in response to pressure changes in the outlet pressure chamber. The first outflow path and the second outflow path each communicate with the recording head and have a first on-off valve that opens and closes the first outflow path and a second on-off valve that opens and closes the second outflow path. [Effects of the Invention]

[0013] According to the first configuration of the present invention, by providing a first on-off valve that opens and closes the first outflow passage and a second on-off valve that opens and closes the second outflow passage, it is possible to selectively discharge the fluid in the outflow pressure chamber. More specifically, by switching the open / close states of the first on-off valve and the second on-off valve to discharge the fluid from only one of the first outflow passage and the second outflow passage, it is possible to accurately select and discharge either the low-density fluid that accumulates in the upper part of the outflow pressure chamber or the high-density fluid that remains in the lower part, thereby improving the discharge efficiency of the desired fluid. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is an explanatory diagram showing the general configuration of a printer 100 as an inkjet recording apparatus according to an embodiment of the present invention. [Figure 2] A plan view of the recording unit 9 included in the printer 100. [Figure 3] 1 is a schematic diagram illustrating the arrangement of an ink flow path 40, a negative pressure adjustment valve 31 connected to the ink flow path 40, and a recording head 17 in a printer 100 according to this embodiment. [Figure 4] Side cross-sectional view of negative pressure adjustment valve 31 [Figure 5] FIG. 1 is a schematic diagram of the negative pressure adjustment valve 31 as viewed from the front side, showing how solid matter S and air A are discharged when a suction purge process is performed. [Figure 6] FIG. 10 is a diagram showing the open / close states of the first on-off valve 44a and the second on-off valve 44b before a predetermined time has elapsed since the start of the suction purge process when the suction purge process is performed in the printer 100 of this embodiment. [Figure 7] FIG. 10 is a diagram showing the open / closed states of the first on-off valve 44a and the second on-off valve 44b after a predetermined time has elapsed since the start of the suction purge process when the suction purge process is performed in the printer 100 of this embodiment. [Figure 8] 10A and 10B are diagrams illustrating other examples of the open / close states of the first on-off valve 44a and the second on-off valve 44b when the suction purge process is performed in the printer 100 of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] 1. Configuration of Inkjet Recording Apparatus Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is an explanatory diagram showing the general configuration of a printer 100 as an inkjet recording device according to an embodiment of the present invention. The printer 100 is equipped with a paper feed cassette 2, which is a paper storage unit. The paper feed cassette 2 is located at the bottom inside the printer main body 1. Inside the paper feed cassette 2, paper P, which is an example of a recording medium, is stored.

[0016] A paper feed device 3 is disposed downstream in the paper transport direction of the paper feed cassette 2, i.e., above the right side of the paper feed cassette 2 in Fig. 1. The paper feed device 3 separates and feeds the paper P one sheet at a time toward the upper right of the paper feed cassette 2 in Fig. 1.

[0017] The printer 100 is equipped with a first paper transport path 4a inside. The first paper transport path 4a is located in the upper right corner, in the paper feed direction, of the paper feed cassette 2. Paper P sent out from the paper feed cassette 2 is transported vertically upward along the side of the printer body 1 by the first paper transport path 4a.

[0018] A pair of registration rollers 13 is provided at the downstream end of the first paper transport path 4a in the paper transport direction. Furthermore, a first transport unit 5 and a recording unit 9 are arranged immediately downstream in the paper transport direction of the pair of registration rollers 13. The paper P sent out from the paper feed cassette 2 passes through the first paper transport path 4a and reaches the pair of registration rollers 13. The pair of registration rollers 13 corrects skewed feed of the paper P and sends the paper P toward the first transport unit 5 (particularly the first transport belt 8, which will be described later) in time with the ink ejection operation performed by the recording unit 9.

[0019] 2 is a plan view of the recording unit 9. The recording unit 9 includes a head housing 10 and line heads 11Y, 11M, 11C, and 11K. The line heads 11Y to 11K are held in the head housing 10 at a height that forms a predetermined gap (for example, 1 mm) with respect to the conveyance surface of an endless first conveyor belt 8 that is stretched over multiple rollers including a drive roller 6a, a driven roller 6b, and a tension roller (not shown). The drive roller 6a causes the first conveyor belt 8 to travel in the conveyance direction of the paper P (the direction of arrow A).

[0020] Each of the line heads 11Y to 11K has a plurality of (three in this example) recording heads 17a to 17c. The recording heads 17a to 17c are arranged in a staggered pattern along the paper width direction (arrow BB' direction), which is perpendicular to the paper transport direction (arrow A direction). Each of the recording heads 17a to 17c has a plurality of ink ejection orifices 18 (nozzles). The ink ejection orifices 18 are arranged at equal intervals along the width direction of the recording head, i.e., the paper width direction (arrow BB' direction). From the line heads 11Y to 11K, inks of yellow (Y), magenta (M), cyan (C), and black (K) are ejected via the ink ejection orifices 18 of the recording heads 17a to 17c toward the paper P transported by the first transport belt 8.

[0021] Four colors of ink (yellow, magenta, cyan, and black) are supplied to the recording heads 17a to 17c constituting each of the line heads 11C to 11K from ink containers 30 (see FIG. 1). A negative pressure adjustment valve 31 (see FIG. 1) is connected between the ink containers 30 and the recording heads 17a to 17c. The detailed configuration of the negative pressure adjustment valve 31 will be described later.

[0022] In response to a control signal from the control device 110 (see FIG. 1), each of the recording heads 17a to 17c ejects ink from the ink ejection openings 18 toward the paper P, which is adsorbed and held on the conveying surface of the first conveyor belt 8 and conveyed, in accordance with image data received from an external computer. As a result, a color image is formed on the paper P on the first conveyor belt 8, with inks of four colors, yellow, magenta, cyan, and black, superimposed on top of each other.

[0023] Returning to FIG. 1, the paper P sent to the first transport unit 5 by the pair of registration rollers 13 is transported by the first transport belt 8 to a position facing the recording unit 9 (particularly recording heads 17a to 17c, which will be described later). Ink is ejected from the recording unit 9 onto the paper P, thereby recording an image on the paper P. The ejection of ink in the recording unit 9 is controlled by a control device 110 inside the printer 100.

[0024] In the paper transport direction, a second transport unit 12 is disposed downstream of the first transport unit 5 (on the left side in FIG. 1). The paper P on which an image has been recorded by the recording unit 9 is sent to the second transport unit 12. The ink ejected onto the surface of the paper P is dried while passing through the second transport unit 12.

[0025] In the paper transport direction, a decurler unit 14 is provided downstream of the second transport unit 12 and near the left side of the printer body 1. The paper P from which the ink has been dried by the second transport unit 12 is sent to the decurler unit 14, where any curl that has occurred in the paper P is straightened.

[0026] In the paper transport direction, a second paper transport path 4b is provided downstream (upper in FIG. 1) of the decurler unit 14. If double-sided recording is not performed, the paper P that has passed through the decurler unit 14 passes through the second paper transport path 4b and is discharged to a paper discharge tray 15 provided outside the left side of the printer 100.

[0027] In addition, a maintenance unit 19 and a cap unit 20 are disposed below the second transport unit 12. When performing purging, the maintenance unit 19 moves horizontally below the recording unit 9, wipes off ink discharged from the ink discharge ports of the recording heads, and collects the wiped ink. Purging refers to the operation of forcibly discharging ink from the ink discharge ports of the recording heads 17a to 17c in order to expel thickened ink, foreign matter, and air bubbles from the ink discharge ports. When capping the ink discharge surfaces of the recording heads, the cap unit 20 moves horizontally below the recording unit 9 and then moves upward to be attached to the undersides of the recording heads 17a to 17c.

[0028] 2. Configuration of ink flow path including negative pressure adjustment valve 3 is a schematic diagram showing the arrangement of an ink flow path 40, a negative pressure adjustment valve 31 connected to the ink flow path 40, and a recording head 17. In the following description, the recording heads 17a to 17c will be simply referred to as recording head 17. The up and down directions in FIGS. 3 and 4 correspond to the vertical direction (the direction of gravity).

[0029] The ink flow path 40 has an ink inlet path 41, a first outlet path 42, and a second outlet path 43. A negative pressure adjustment valve 31 is connected between the ink inlet path 41 and the first and second outlet paths 42 and 43.

[0030] The first outlet path 42 is connected to a first discharge hole 51a (see FIG. 4) formed in the outlet pressure chamber 51 of the negative pressure adjustment valve 31, and connects the outlet pressure chamber 51 and the recording head 17.

[0031] The second outlet path 43 is connected to a second discharge hole 51b (see FIG. 4) formed in the outlet pressure chamber 51, and connects the outlet pressure chamber 51 to the recording head 17. The first outlet path 42 and the second outlet path 43 join at a joining portion 48 and are then connected to the recording head 17.

[0032] A first on-off valve 44a that opens and closes the first outflow path 42 is provided in the first outflow path 42 between the negative pressure adjustment valve 31 and the junction 48. A second on-off valve 44b that opens and closes the second outflow path 43 is provided in the second outflow path 43 between the negative pressure adjustment valve 31 and the junction 48. The first on-off valve 44a and the second on-off valve 44b are switchable between an open state in which the first outflow path 42 and the second outflow path 43 are completely opened, a closed state in which the first outflow path 42 and the second outflow path 43 are completely closed, and a half-open state in which the first outflow path 42 and the second outflow path 43 are opened by a predetermined percentage (for example, 50%).

[0033] Ink introduced into the ink flow path 40 from the ink container 30 (see FIG. 1) is supplied to the recording head 17 via the ink inflow path 41, the negative pressure adjustment valve 31, the first outflow path 42, the second outflow path 43, and the junction 48. A pressure pump 33 is connected to the ink inflow path 41. The pressure pump 33 maintains the internal pressure of the inflow side pressure chamber 50 (see FIG. 4) of the negative pressure adjustment valve 31 at a constant pressure higher than the internal pressure of the outflow side pressure chamber 51 (see FIG. 4).

[0034] It is also possible to adopt a configuration in which the pressure inside the inlet pressure chamber 50 is maintained at a constant pressure by using the ink head pressure, by locating the ink container 30 at a position higher than the negative pressure adjustment valve 31, without providing the pressure pump 33. Furthermore, if a sub-tank (not shown) is located between the ink container 30 and the negative pressure adjustment valve 31, the sub-tank may be located at a position higher than the negative pressure adjustment valve 31.

[0035] A cap 201 is attached to the recording head 17. The cap 201 is supported by a cap unit 20 (see FIG. 1) and is attached to the ink ejection surface (nozzle surface) 171 of the recording head 17 when printing processing is not performed for a certain period of time or more. By attaching the cap 201, the ink ejection surface 171 of the recording head 17 is kept sealed. The cap 201 is provided with a flow path (not shown) that communicates with the atmosphere. This flow path can be opened and closed, and prevents excessive pressure changes from occurring in the nozzles of the recording head due to temperature changes in the space between the ink ejection surface 171 and the cap 201. A suction pump 45 and a waste ink discharge flow path 47 are connected to the cap 201.

[0036] In the printer 100, in order to remove dried or thickened ink and foreign matter from inside the ink ejection ports 18 (see FIG. 2) of the recording head 17, when starting printing after a long period of inactivity or between printing operations, a cap 201 is attached to the ink ejection surface 171, and with the flow path communicating with the atmosphere closed, a suction purge process is performed in which the air is sucked from the space (sealed space) between the ink ejection surface 171 and the cap 201 using the suction pump 45 to forcibly suck ink from all of the ink ejection ports 18 of the recording head 17, in preparation for the next printing operation. The ink sucked into the cap 201 from the recording head 17 (purged ink) is discharged outside the cap 201 by the suction pump 45 and then collected in a waste ink tank (not shown) via a waste ink discharge flow path 47.

[0037] The suction purge process is also performed when initially filling the ink flow path 40 with initial filling liquid or ink, when replacing the ink flow path 40 filled with initial filling liquid with ink, and when discharging air or foreign matter from the ink flow path 40.

[0038] In this embodiment, the first outflow path 42 and the second outflow path 43 join at a joining portion 48 and then communicate with the recording head 17. In this configuration, the fluid in the first outflow path 42 and the second outflow path 43 is sucked through the recording head 17 by the suction pump 45 and flows out to the waste ink discharge path 47. Therefore, the pressure applied inside the outflow pressure chamber 51 becomes higher than the pressure applied to the ink ejection ports (nozzles) 18 of the recording head 17. Therefore, even if the absolute value of the negative pressure applied by the suction pump 45 is increased, there is no risk of the meniscus in the ink ejection port 18 being drawn in and air bubbles entering the ink ejection port 18.

[0039] [3. Configuration of the negative pressure adjustment valve] 4 is a side cross-sectional view of the negative pressure adjustment valve 31 used in the printer 100 of this embodiment. The negative pressure adjustment valve 31 stores ink flowing through the ink flow path 40 and functions as a pressure adjustment valve that opens and closes the ink flow path 40 in accordance with the pressure on the recording head 17 side. The negative pressure adjustment valve 31 has an inlet pressure chamber 50, an outlet pressure chamber 51, a valve member 52, and an opening / closing pressure adjustment spring 53.

[0040] The inlet pressure chamber 50 has an ink inlet hole 50a to which the ink inlet channel 41 is connected. The inlet pressure chamber 50 has a predetermined volume for storing ink that flows in from the ink inlet hole 50a. The inlet pressure chamber 50 is connected to the outlet pressure chamber 51 by a communication hole 54. The inlet pressure chamber 50 contains one end (large diameter portion) of a valve member 52 that can close the communication hole 54, and an opening / closing pressure adjustment spring 53.

[0041] The outflow pressure chamber 51 has a first outflow hole 51a to which the first outflow path 42 is connected, a second outflow hole 51b to which the second outflow path 43 is connected, and a diaphragm portion 55. The outflow pressure chamber 51 stores ink that has flowed in from the communication hole 54. The volume of the outflow pressure chamber 51 changes depending on the displacement of the diaphragm portion 55.

[0042] The first outlet hole 51a is connected to the recording head 17 via the first outlet path 42. The first outlet hole 51a is formed at a position lower than the communication hole 54. In this embodiment, the first outlet hole 51a is formed at the lower end of the outlet-side pressure chamber 51.

[0043] The second outlet hole 51b is connected to the recording head 17 via the second outlet path 43. The second outlet hole 51b is formed at a position higher than the communication hole 54. In this embodiment, the second outlet hole 51b is formed at the upper end of the outlet-side pressure chamber 51. The outlet-side pressure chamber 51 accommodates the other end (small diameter portion) of the valve member 52 and a pressure-receiving plate 56.

[0044] The valve member 52 is movable between a closed position where it closes the communication hole 54 and an open position where it opens the communication hole 54 against the biasing force of the opening / closing pressure adjustment spring 53, in response to pressure changes in the outlet pressure chamber 51. An O-ring 58 is attached to the opening of the communication hole 54 on the inlet pressure chamber 50 side. When the valve member 52 is positioned in the closed position, one end (large diameter portion) of the valve member 52 comes into contact with the O-ring 58. When the valve member 52 is positioned in the open position, one end (large diameter portion) of the valve member 52 is separated from the O-ring 58.

[0045] The diaphragm portion 55 is formed from a laminated flexible resin film. The diaphragm portion 55 is fixed to the outer surface of the outlet pressure chamber 51 with a predetermined amount of slack. The diaphragm portion 55 displaces in response to pressure changes within the outlet pressure chamber 51, changing the volume of the outlet pressure chamber 51.

[0046] The pressure plate 56 is fixed to the inner surface of the diaphragm portion 55 (the resin layer facing the outlet-side pressure chamber 51) and is movable integrally with the diaphragm portion 55. The other end (small diameter portion) of the valve member 52 inserted into the communication hole 54 abuts against the center position of the pressure plate 56. A force acts on the pressure plate 56 via the valve member 52 by the biasing force of the opening / closing pressure adjustment spring 53 in a direction that displaces (expands) the diaphragm portion 55 outward.

[0047] As ink is consumed in the recording head 17 and the pressure in the outlet pressure chamber 51 decreases, the diaphragm portion 55 is displaced inward (contracts). This causes the pressure receiving plate 56 to press the valve member 52 into the inlet pressure chamber 50 (open position) against the biasing force of the opening / closing pressure adjusting spring 53, opening the communication hole 54. As a result, ink is supplied from the inlet pressure chamber 50 to the outlet pressure chamber 51. When the inside of the outlet pressure chamber 51 reaches a predetermined negative pressure, the valve member 52 is pushed back into the outlet pressure chamber 51 (closed position), closing the communication hole 54 and stopping the supply of ink from the inlet pressure chamber 50 to the outlet pressure chamber 51. In this way, the pressure of ink supplied to the recording head 17 is adjusted.

[0048] When performing the suction purge process, the ink ejection surface 171 of the recording head 17 is covered with the cap 201, and with the flow path that connects the inside of the cap 201 to the atmosphere closed, the suction pump 45 sucks the space (sealed space) between the ink ejection surface 171 and the cap 201 to generate negative pressure. This moves the valve member 52 to the open position to open the communication hole 54, and the liquid (ink or initial filling liquid) inside the recording head 17 is discharged from the ink ejection ports 18.

[0049] At this time, the outlet pressure chamber 51 in the negative pressure adjustment valve 31 becomes negative pressure, and the valve member 52 is pressed by the diaphragm portion 55. As a result, the valve member 52 moves into the inlet pressure chamber 50 against the biasing force of the opening / closing pressure adjustment spring 53, opening the communication hole 54 and connecting the inlet pressure chamber 50 to the outlet pressure chamber 51. This causes liquid to flow from the ink container 10 through the ink inlet channel 41, the negative pressure adjustment valve 31, the first outlet channel 42, the second outlet channel 43, and the junction 48 to the recording head 17.

[0050] 5 is a schematic diagram of the negative pressure adjustment valve 11 as viewed from the front side (left side of FIG. 4), illustrating how liquid (initial filling liquid or ink) and air are discharged during the suction purge process. Solid matter S, such as solidified ink components and foreign matter contained in the liquid that flows from the communication hole 54 into the outlet pressure chamber 51 during the suction purge process, accumulates at the bottom of the outlet pressure chamber 51. Therefore, the solid matter S flows out of the first outlet hole 51a formed at the bottom of the outlet pressure chamber 51, through the first outlet path 42 and the junction 48, and into the recording head 17.

[0051] Furthermore, air A contained in the liquid flowing into the outlet pressure chamber 51 accumulates in the upper part of the outlet pressure chamber 51. As a result, air A flows out from the second outlet hole 51b formed in the upper part of the outlet pressure chamber 51, through the second outlet path 43 and the junction 48, and into the recording head 17.

[0052] According to the configuration of this embodiment, the solid matter S in the outlet pressure chamber 51 flows out smoothly and efficiently from the first outlet hole 51a, which is located below the communication hole 54, through the first outlet path 42, and does not remain in the outlet pressure chamber 51. Furthermore, the air A in the outlet pressure chamber 51 flows out smoothly and efficiently from the second outlet hole 51b, which is located above the communication hole 54, through the second outlet path 43, and does not remain in the outlet pressure chamber 51.

[0053] Furthermore, when performing a suction purge process during installation of the printer 100 to replace the initial filling liquid in the ink flow paths 40 with ink, the initial filling liquid, which has a low density, flows out smoothly and efficiently from the second outflow holes 51b, which are located above the communication holes 54, through the second outflow paths 44. Therefore, the initial filling liquid does not remain in the outflow pressure chambers 51.

[0054] Therefore, it is possible to improve the discharge performance of both the low-density fluid (air or initial filling liquid 9) remaining in the upper part of the outflow-side pressure chamber 51 and the high-density fluid (ink containing solid matter S) remaining in the lower part.

[0055] In addition, in this embodiment, by providing a first opening / closing valve 44a that opens and closes the first outflow path 42 and a second opening / closing valve 44b that opens and closes the second outflow path 43, it is possible to selectively discharge the fluid in the outflow side pressure chamber 51.

[0056] More specifically, by switching the open / close states of the first on-off valve 44a and the second on-off valve 44b to allow the fluid to flow out from only one of the first outflow path 42 and the second outflow path 43, it becomes possible to accurately select and outflow either the low-density fluid accumulating in the upper part of the outflow-side pressure chamber 51 or the high-density fluid remaining in the lower part, thereby improving the efficiency of discharging the desired fluid. The open / close states of the first on-off valve 44a and the second on-off valve 44b will be described in detail below.

[0057] 6 and 7 are diagrams showing the open and closed states of the first on-off valve 44a and the second on-off valve 44b before and after a predetermined time has elapsed since the start of the suction purge process when the suction purge process is performed in the printer 100 of this embodiment. Figures 6 and 7 show the case where the suction purge process is performed before shipping the printer 100, and the ink flow paths 40 are filled with initial fill liquid or ink from an empty state. Also, in Figures 6 and 7, the open and closed states of the first on-off valve 44a and the second on-off valve 44b are shown in white and black, respectively.

[0058] When filling the ink flow path 40 with initial filling liquid or ink from an empty state, the first on-off valve 44a is closed and the second on-off valve 44b is open for a certain period of time after the start of the suction purge process, as shown in Figure 6. This causes the fluid in the outflow pressure chamber 51 to flow only from the second outflow hole 51b to the second outflow path 43, rather than from the first outflow hole 51a to the first outflow path 42. As a result, air remaining in the upper part of the outflow pressure chamber 51 is discharged from the second outflow hole 51b to the second outflow path 43, through the recording head 17, and into the waste ink discharge path 47.

[0059] After a certain time has elapsed since the start of the suction purge process, the suction purge process is continued with the first on-off valve 44a in the open state and the second on-off valve 44b in the closed state, as shown in Fig. 7. This executes a normal purge in which liquid flows from the first outflow hole 51a through the first outflow path 42 to the recording head 17, thereby filling the recording head 17 with initial filling liquid or ink.

[0060] By performing the suction purge process as described above, the air inside the negative pressure adjustment valve 31 can be discharged more efficiently, and the flow rate of the initial filling liquid or ink flowed to fill the ink flow path 40 can be reduced.

[0061] Furthermore, when a suction purge process is performed upon installation of the printer 100 to replace the initial filling liquid in the ink flow paths 40 with ink, or when air bubbles that have become mixed into the ink flow paths 40 after the printer 100 has started to be used are discharged, it is preferable to close the first on-off valve 44a and open the second on-off valve 44b for only a certain period of time at the beginning of the suction purge process, as shown in Fig. 6, and then, after the certain period of time has elapsed, to open the first on-off valve 44a and close the second on-off valve 44b, as shown in Fig. 7. The operation of opening the on-off valve 44 for only a certain period of time at the beginning of the suction purge process may be performed every time the suction purge process is performed, or may be performed every time a predetermined number of suction purge processes are performed (once every multiple times).

[0062] By performing the suction purge process as described above, the initial filling liquid remaining in the upper part of the outlet pressure chamber 51 is discharged from the second outlet hole 51b through the second outlet path 43 and the recording head 17 to the waste ink discharge path 47. Therefore, the initial filling liquid inside the negative pressure adjustment valve 31 can be discharged more efficiently, and the flow rate of ink flowing to replace the initial filling liquid with ink can be reduced.

[0063] On the other hand, when performing a suction purge process to discharge solidified ink components or foreign matter that has accumulated in the ink flow path 40 while the printer 100 is in use, it is preferable to perform the suction purge process with the first on-off valve 44a in the open state and the second on-off valve 44b in the closed state, as shown in Figure 7.

[0064] As a result, solidified ink components and foreign matter remaining in the lower part of the outflow pressure chamber 51 are discharged from the first outflow hole 51a through the first outflow path 42 and the recording head 17 to the waste ink discharge path 47. Therefore, solidified ink components and foreign matter inside the negative pressure adjustment valve 31 can be discharged more efficiently, and the flow rate of ink flowing to discharge solidified ink components and foreign matter can be reduced.

[0065] Furthermore, by discharging fluid from the outlet pressure chamber 51 with at least one of the first and second opening / closing valves 44a and 44b in a half-open state, it is possible to suppress the outflow of either the low-density fluid (air or initial filling liquid) that remains in the upper part of the outlet pressure chamber 51 or the high-density fluid (ink) that remains in the lower part, thereby improving discharge efficiency.

[0066] 8 is a diagram showing another example of the open / close states of the first on-off valve 44a and the second on-off valve 44b when a suction purge process is performed in the printer 100 of this embodiment. For example, when a suction purge process is performed to discharge solidified ink components and foreign matter, the suction purge process is performed with the first on-off valve 44a in an open state (white) and the second on-off valve 44b in a half-open state (black and white), as shown in FIG.

[0067] As a result, the flow path resistance when the fluid flows out from the first outlet hole 51b is smaller than the flow path resistance when the fluid flows out from the second outlet hole 51b, and ink containing solid matter that has accumulated in the lower part of the outlet pressure chamber 51 is preferentially discharged. Therefore, it is possible to achieve the dischargeability of both the low-density fluid (air or initial filling liquid) that has accumulated in the upper part of the outlet pressure chamber 51 and the high-density fluid (ink containing solid matter) that has accumulated in the lower part, thereby improving discharge efficiency.

[0068] Furthermore, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention. For example, in the above-described embodiments, the recording head 17, the negative pressure adjustment valve 31, and the suction pump 45 are exemplified as components connected to the ink flow path 40, but the present invention is also applicable to configurations in which other components are connected to the ink flow path 40.

[0069] In addition, in the above embodiment, an example was described in which a color printer that records color images using four colors of ink was used as the inkjet recording device, but the ink supply unit of this embodiment can also be used when a monochrome printer that records monochrome images using black ink is used. [Industrial Applicability]

[0070] The present invention can be used in inkjet recording devices such as inkjet printers that are provided with a negative pressure adjustment valve between an ink container and a recording head. [Explanation of symbols]

[0071] 10 Ink Container 17, 17a to 17c recording head 18 Ink outlet (nozzle) 31 Negative pressure adjustment valve 33 Pressure pump 40 Ink flow path 41 Ink inlet 42 1st outflow channel 43 2nd outflow channel 44a First shut-off valve 44b Second shut-off valve 45 Suction Pump 47 Waste ink discharge flow path 48 Junction 50 inlet pressure chamber 51 Outlet pressure chamber 52 Valve member 53 Opening / closing pressure adjustment spring (biasing member) 54 Communication hole 55 Diaphragm part 56 Pressure plate 100 Printers (inkjet recording devices) A. Air S solids

Claims

1. an ink container for storing ink; one or more recording heads each having a plurality of nozzles for ejecting the ink; an ink flow path that connects the ink container and the recording head; a negative pressure adjustment valve connected to the ink flow path; a cap that is attached to the ink ejection surface of the recording head and that can form a sealed space between the cap and the ink ejection surface; a suction pump that sucks air from inside the cap; a waste ink discharge flow path that discharges the liquid sucked into the inside of the cap by the suction pump; Equipped with an inkjet recording apparatus capable of performing a suction purge process in which, with the cap attached to the ink ejection surface, the air in the sealed space is sucked by the suction pump, and the ink is forcibly discharged from all the nozzles of the recording head, The negative pressure regulating valve is an inlet pressure chamber having an ink inlet hole communicating with an ink inlet path, which is the ink flow path on the ink container side; an outflow pressure chamber communicating with an ink outflow path, which is the ink flow path on the recording head side; a communication hole that communicates the inlet pressure chamber with the outlet pressure chamber; a first outlet hole formed below the communication hole of the outlet pressure chamber and communicating with a first outlet path that is the ink outlet path; a second outlet hole formed above the communication hole of the outlet pressure chamber and communicating with a second outlet path that is the ink outlet path; a valve member that is inserted into the communication hole and that is movable between a closing position where the communication hole is closed and an opening position where the communication hole is opened in response to a pressure change in the outlet pressure chamber; and the first outlet path and the second outlet path each communicate with the recording head; a first on-off valve that opens and closes the first outflow path; a second on-off valve that opens and closes the second outflow path; An inkjet recording apparatus comprising:

2. 2. The ink jet recording apparatus according to claim 1, wherein the suction purge process is performed with one of the first on-off valve and the second on-off valve in an open state and the other in a closed state.

3. When the suction purge process is performed in a state where the ink flow path is empty, the ink flow path is filled with the initial filling liquid or the ink, 3. The inkjet recording apparatus according to claim 2, wherein the first opening / closing valve is closed and the second opening / closing valve is open for a predetermined time from the start of the suction purge process, and after the predetermined time has elapsed, the first opening / closing valve is opened and the second opening / closing valve is closed to continue the suction purge process.

4. When the suction purge process is performed in a state where the ink flow path is filled with initial filling liquid, the initial filling liquid in the ink flow path is replaced with the ink, 3. The inkjet recording apparatus according to claim 2, wherein the first opening / closing valve is closed and the second opening / closing valve is open for a predetermined time from the start of the suction purge process, and after the predetermined time has elapsed, the first opening / closing valve is opened and the second opening / closing valve is closed to continue the suction purge process.

5. When the suction purge process is performed to discharge solid matter remaining in the ink flow path, 3. The ink jet recording apparatus according to claim 2, wherein the suction purge process is performed with the first on-off valve in an open state and the second on-off valve in a closed state.

6. 2. The ink jet recording apparatus according to claim 1, wherein the suction purge process is performed with at least one of the first on-off valve and the second on-off valve in a half-open state.

7. When the suction purge process is performed to discharge solid matter remaining in the ink flow path, 7. The ink jet recording apparatus according to claim 6, wherein the suction purge process is performed with the first on-off valve in an open state and the second on-off valve in a half-open state.

8. The negative pressure regulating valve is a diaphragm portion that constitutes a part of the outlet pressure chamber and that changes the volume of the outlet pressure chamber by being displaced in response to a pressure change in the outlet pressure chamber; a biasing member that biases the valve member toward the closed position; and 2. The ink jet recording apparatus according to claim 1, wherein the valve member moves between the closed position and the open position due to displacement of the diaphragm portion and the biasing force of the biasing member.

9. When the suction purge process is performed to discharge air bubbles that have entered the ink flow path, 2. The inkjet recording apparatus according to claim 1, wherein the on-off valve is opened for a predetermined time from the start of the suction purge process each time the suction purge process is performed or each time the suction purge process is performed a predetermined number of times, and after the predetermined time has elapsed, the on-off valve is closed to continue the suction purge process.

Images